Efficacy of removal of cariogenic bacteria and carious dentin by ablation using different modes of Er:YAG lasers

Abstract

The primary objective of this in vitro study was to evaluate the efficiency of removal of cariogenic bacteria and carious dentin by ablation using two lasers: fluorescence-feedback controlled (FFC) Er:YAG laser and different pulses of Er:YAG laser based on variable square pulse technology (VSPt). The secondary objective was to measure the temperature during laser ablation of carious tissue. Seventy-two extracted human molars were used in this study. Sixty teeth with carious dentin were randomly divided into four experimental groups according to the treatment for caries removal: group 1: 400 µs (FFC group); group 2: super short pulse (SSP group, 50 µs pulse); group 3: medium short pulse (MSP group, 100 µs pulse); group 4: short pulse (SP group, 300 µs pulse) and one positive control group with no treatment. Twelve teeth without carious lesion were used as a negative control group. After caries removal, swabs were taken with cotton pellets and real-time PCR analysis was performed. During caries ablation, a thermal infrared camera was used to measure the temperature changes. In all experimental groups, specimens were free of bacterial contamination after the treatment. In the SSP, MSP and SP groups, temperatures measured during caries ablation were significantly higher compared to temperatures in the FFC group (P<0.001). In this in vitro study, laser treatment for removal of carious dentin and cariogenic bacteria was an efficient treatment modality without causing excessive temperatures that might adversely affect pulp vitality.

Use of the Er:YAG Laser in Conservative Dentistry: Evaluation of the Microbial Population in Carious Lesions

“…To preserve the vitality of the pulp, working times are reduced, developing lowest heat doses. Er:YAG decontaminating properties allow the maximum optimization of residual tissues and a minimally invasive approach with less risk of pulpal exposure [ 18 ]; however, further investigations are needed to assess the amount of residual healthy dentine. It should be emphasized that Er:YAG lasers recognize deciduous tooth structures as an advantageous target, with lower thickness, more porous surface, and higher water and chromophores content, reaching a higher cutting power [ 38 ].…”

“…In particular, Er:YAG therapy is a commonly used system for hard dental tissue ablation, since Erbium wavelength coincides with the absorption peak of water and hydroxyapatite, causing the removal of mineralized dental substance through micro-explosions [ 17 ]. Furthermore, compared to the healthy one, carious tissue contains even more water, so the Er:YAG laser has higher chromophores absorption on infected tissues, and it well represents a selective and conservative device for caries removal, allowing the creation of a therapeutic cavity preparation without excessive extension in healthy tissues below the lesion [ 18 ]. The Er:YAG laser combines photoablative and decontaminating properties with minimally invasive characteristics.…”

“…Because of this, the benefits of treating a carious lesion with Er:YAG, compared to conventional therapy (CT), not only include less vibrations and noises for the patient, but above all bactericidal and bacteriostatic properties [ 19 ] due to high temperatures developed during irradiation. In fact, the photothermal effect developed during the ablation can be responsible for the disinfection of residual bacteria in the cavities, without causing thermal damage to the dental pulp [ 18 ]. Finally, it has to be considered that laser irradiation melts inorganic components of dentin and can also cause remineralisation [ 20 , 21 , 22 ].…”

Minimally invasive treatment of dental caries, an update

“…It gives pulsed shots, each of which is in the nano-second range, such laser radiation, when fired on a tissue, causes evaporation of the water at the irradiated point resulting in a micro explosion of the surrounding hard tissue [29] . The excitation wavelength induces a fluorescence signal that has been assigned to protoporphyrin, a bacterial degradation product [30] . This process is known as ablation.…”

Effect of <i>Q</i>-switched Er:YAG laser irradiation on bonding performance to dentin surface

“…In particular, laser was shown to be more comfortable 6) and selective compared with rotational instruments drilling 7,8) . Furthermore, it showed some antibacterial effects that can increase effectiveness in caries removal 9,10) . Nevertheless, several drawbacks, including prolonged working times, thermal increase, and questionable dental structure alterations have been highlighted 11,12) .…”